Posted by Priscilla on Friday, December 25, 2009 at 10:43pm.
A race car can be slowed with a constant acceleration of 11 m/s^2
a. If the car is going 55 m/s, how many meters will it travel before it stops?
b. How many meters will it take to stop a car going twice as fast?

Physics  Damon, Saturday, December 26, 2009 at 4:18am
v = Vo + a t
so
v = 55  11 t
when is v = 0 ?
0 = 55  11 t
so t = 5 seconds to stop
d = Vo t + (1/2) a t^2
d = 55 (5)  (1/2) 11 (25)
= 275  137.5
=137.5 meters
Now do that again for Vo = 110 m/s 
Physics  Heart, Saturday, December 26, 2009 at 8:49am
Ok, thanks but i don't understand b. I know you use the equation d = Vit +1/2 at^2 but to find the distance would you just calculate d = vit only.

Physics  Damon, Saturday, December 26, 2009 at 2:03pm
No, do v = Vo + a t again with
0 = 110  11 t
then use that t in
d = 110 t  (1/2)11 t^2